Slot type reed valve



Nov. 22, 1966 D. K. STEPHENSON SLOT TYPE REED VALVE Filed March 27, 1963INVENTOR.

W, M24 m ATTORNEY? United States Pfltfiflt F Filed Mar. 27, 1963, Ser.No. 268,362 2 Claims. 01. 131-s2s.s

The invention relates to reed valves. Generally speaking, a reed valveis a form of check valve comprising a flexible valve leaf or reed membermounted at one side of a port. and operated by pressure differential toand from engagement with a seat to control flow'through the port. Inmoving from its open position to its closed pOSltion, the reed memberdoes not pivot upon a fixed axis but upon an axiswhich progressivelyapproaches the port.

The invention seeks to attain increased reed member life by reducing asfar as possible such stress loading as occurs during operation. Moreparticularly, increased reed member life is attained in accordance withthe invention by means providing for the elimination of, or at least areduction in, reed member failure by reason of the formation of cracksor fissures extending inwardly from the periphery of the reed member.Such failure is believed to be occasioned by fatigue resulting fromrepeated heavy stress loading. 7

Reed valves are employed in many areas, including combustion air-intakearrangements in engines such as chain saw engines and outboard motorengines, which engines often operate at rates as high as 4,800 cyclesper minute and sometimes at higher speeds. While the pressure conditionscausing reed valve operation are generally not very high, it is commonfor the reed member to dish into the port after closure of the valve.Such dishing generally involves curvature about more than one axis andraisin-g of at least a portion of the reed periphery from the seat andinto an area of less magnitudethan that which it occupied when flat.Such action creates a fluted or undulating configuration along the reedmember periphery. As a result, it is believed that relatively heavystresses are created, particularly in the form ofstress waves along theperiphery of the reed.

Reduction of the maximum stress loading occurring during each cycle canbe obtained in accordance with the invention in several ways which, whencombined, cooperate to provide optimum reduction in the maximum stressexperienced during. each operationalcycle.

A very significant contribution to maximum stress reduction can beobtained by limiting the amount or extent of lap between the peripheryof the reed member and its associated seat. In this regard, the lesserthe amount of lap, the lesser the extent to which the reed memberperiphery is raisable from the valve seat in response to dishing of thereed member into the port. Such lap is desirably limited to within arange from about .045 inch to about .010 inch. The lower figurerepresents a practical limit from the viewpoint of manufacturingtolerance and effective operation. Use of a lap of about .020 inch hasbeen found to provide a significant increase in reed member life, ascompared with conventional valves in least .065 inch and is commonlysubstantially in excess of .065 inch. which the lap between the reedmember and the seat isat Limitation of lap between the reedrnernberandthe seat surrounding the port has also been found to result in anincreased amount of wear along the periphery of the reed member, atleast during initial operation of the reed valve. As fatigue isconsidered, at least initially, to be a surface condition, it ispossible that the rate of wear is faster, when a limited lap isemployed, than the rate of development of fatigue in the wearingsurface. It isialso "ice possible that such wear serves to work hardenthe lapping surface of the reed member and thereby inhibit thedevelopment of a fatigue in the wearing surface.

Reduction in valve'member stress can also be obtained in accordance withthe invention by formation of the reed member and its associated portand seat so as to limit reed member fiexure, when the reed member is inportclosing position, either by substantially preventing dishing, or bysubstantially limiting such dishing to fiexure about a single axis.Prevention of reed member dishing or fiexure, when the reed member isseated, can be obtained by formation of the port with a seat which, withrespect to the reed member, is convexly curved about a single axisextending parallel to the axis about which the reed member flexes toclose the port. Consequently, during progressive closing of the port,the reed member assumes a curvature which serves to rigidify it againstcurvature about more than one axis, therefore tending to precludedisplacement or dishing inwardly of the port. Alternatively, the reedmember can be preformed to provide rigidity against fiexure about morethan one axis.

Limitation of dishing to curvature about a single axis can be obtainedin large measure by formation of the port so that all or a substantialportion of the edge of the port lies in the surface of an imaginarycurved surface, such as for example, a cylindrical or hyperbolicsurface, which surface is concave with respect to the reed member. Onearrangement for accomplishing this result employs an elongated portconfiguration with at least one rectilinear edge which extendslengthwise of the port and which tends to serve to establish reed memberfiexure about a single axis parallel to said edges along the major partof the length of the port inwardly of the ends of the port. With thisconfiguration, reed member flexure can be limitedat the ends of theport-closing portion to curvature about a single axis by forming the endedges of the port so as to lie in an imaginary curved surface whichincludes said rectilinear edge. For best results, the edge of the portopposite to said rectilinear edges also lies in said imaginary curvedsurface.

Increased stress reduction can also be obtained in accordance with theinvention by reduction in impact occurring incident to seating of thereed member. Reduction in impact can be obtained either by reducing thereed valve velocity at the time of impact or by extending the timeinterval of impact.

Reduction in reed member velocity at the time of impact can be obtainedby limiting the area of the reed member which is subject to the pressuredifferential causing reed member travel relative to its seat. Onearrangement for attaining this result is to limit lap. Anotherarrangement includes provision for porting the reed member in the areabetween its hinged connection to the rigid member and the adjacent edgeof the controlled port. Such limitation of lap and porting of the reedmember 1 serve to reduce the over-all reed member area subject to theaction of any pressure differential. Consequently, the applied force andresultant velocity relative to the valve seat is also reduced. Reductionin impact stress can also be obtained by providing resiliency in thevalve seat so as to lengthen the time interval of impact. Resilientseats can also be used to assist in obtaining single-axis flexure.

Other objects and advantages of the invention will become known byreference to the following description and accompanying drawings.

In the drawings:

FIGURE 1 is a partially broken away elevational view of a reed valve inaccordance with the invention;

FIGURE 1a is an enlarged sectional view of a portion of the reed valveshown in FIGURE 1, showing the disposition of the reed member relativeto the reed plate during gas flow through the reed valve;

FIGURE lb is a view similar to FIGURE la, showing the relation of thereed member to the reed plate immediately upon engagement of the reedmember with the reed plate and just prior to disengagement of the reedmember from the plate;

FIGURE 10 is a view similar to FIGURES la and lb, showing thedisposition of the reed member when seated against the port in the reedplate and flexed inwardly of the port;

FIGURE 2 is an exploded perspective view of the reed valve shown inFIGURE 1;

FIGURE 3 is a sectional view taken along line 3-3 of FIGURE 1;

FIGURE 4 is a fragmentary sectional view of a modified form of reedplate;

FIGURE 5 is a fragmentary elevational view of a reed valve embodying thereed plate shown in FIGURE 4;

FIGURE 6 is a fragmentary sectional View of another modified reed plate;

FIGURE 7 is a fragmentary elevational view of a reed valve embodying thereed plate shown in FIGURE 6;

i in less remote relation to the boundary line 24. At its ends, the portis defined by end or side edges' 29 and 31 which are generally parallelto each other, which are substantially normal to the lengthwise edges 25and 27, and which merge through small radii, indicated at 33, into theouter and inner lengthwise edges 25 and 27, respectively.

Use of an elongated port, as disclosed above, serves to limit flexure ofthe portion 20 of the reed member inwardly of the port 17, when the reedmember is seated against the plate in port-closing relation thereto, tocurvature about only one axis along a major portion of the length of theport inwardly of the end edges 29 and 31 of the port. Such flexing ofthe port-closing portion 20 of the reed member inwardly of the port 17is believed to be primarily caused by momentum of the reed member, butis also believed to be due in part to the existing pressuredifl'erential.

Flexure of the port-closing portion 20 of the reed member 19 adjacent tothe end edges 29 and 31 of the port 17 can be substantially limited tocurvature about. the single axis mentioned immediately above by variousmeans.

Specifically, as shown in FIGURES 4 through 7, the valve FIGURE 8 is afragmentary sectional view of still an- 7 other modified reed plate;

FIGURE 9 is a fragmentary elevational view of a reed valve incorporatingthe reed plate shown in FIGURE 8;

FIGURE 10 is an enlarged fragmentary view of still another modified reedvalve; and

FIGURE 11 is a fragmentary sectional view of still another modified reedvalve. a

The reed valve 11 shown in FIGURE 1 of the drawings is exemplary ofvarious arrangements and configurations that can be used in accordancewith the invention. The reed valve 11 includes a rigid member or plate15 having therein a port or aperture 17, a relatively flexible valveleaf or reed member 19 which is fixed to the plate 15 and includes aport-closing portion 20 movable relative to the plate 15 to open andclose the port 17, together with a leaf stop 21 which is fixed to theplate 15 and which serves to limit opening movement of the reed member19 away from the plate 15. The leaf stop 21 can be fabri cated of anyrigid material, such as for example, brass or steel, and can be ofvarious configurations.

While various arrangements can be used to unite the reed member 19 andthe leaf stop 21 to the plate 15, the disclosed construction utilizes aseries of laterally. aligned screws 23 which can serve to establish anarea of permanent engagement between the reed member 19 and the plate15. During movement between its open and closed positions, the reedmember 19 flexes relative to the area of permanent engagement about anaxis which progressively moves from the boundary line of the area ofpermanent engagement toward the outer or free end of the reed memberuntil closure of the reed member against the plate 15 is complete. theleaf stop 21 is fabricated and assembled to the reed plate so as toestablish a boundary line 24 limiting the area of permanent engagementof the reed member 19 with the plate 15. Preferably, the boundary line24 is essentially rectilinear.

The plate 15 can be formed in various ways, as for instance, by aluminumdie casting. Suitable arrangements not material to the invention can beprovided for securing the plate 15 about an opening in a housing, suchas a crankcase, which housing is subject to cyclical pressure variationabove and below a pressure condition exterior to the housing.

The port 17 is elongated in generally parallel relation to the boundaryline 24 of permanent engagement. The port includes an outer rectilinearedge 25 which extends lengthwise of the port 17 in remote, generallyparallel relation to the boundary line 24. The port 17 also includes asecond or inner rectilinear edge 27 extending in parallel, opposedrelation to the outer rectilinear edge 25 In the disclosed construction,

seat portions at the margins of the plate 15 at the end edges 29 and 31can be concavely dished with respect to the plane of the plate so as toconform generally to the curvature of the port-closing portion 20 of thereed member 19 about the before-mentioned axis when flexure of thelengthwise edges 25 and 27. The curvature of the recesses 35 correspondsto the curvature of the central part of the reed member port-closingportion 20 when the flexure of the reedmember inwardly of the port is atits normal maximum, thereby permitting flexure of the end parts 20a ofthe port-closing portion in substantially like manner to the flexure ofthe central part 20b of the reed member port-closing portion.

In the embodiment shown in FIGURES 6 and 7, the reed plate 15 isprovided with a concavely dished recess 37 which includes marginalportions 39 and 41 of the feed plate extending along the respectiveedges 25 and 27, as well asmarginal portions 43 of the reed plate at theends of the port 17. Preferably, the outer edge 45 of the recess 39terminates in the area where the outer edge of the reed member 19initially engages the reed plate 15 during port-closing operation andbefore flexure of the reed member inwardly of the port.

Limitation of reed member flexure at the ends of the port-closingportion 20 curvature about a single axis extending lengthwise of theport-closing portion can alternatively. or additionally be obtained byusing resilient in-- serts at the ends of the port 17. Such inserts canbe a fabricate of materials such as nylon to permit conformance of thelapped margins of the inserts to the tendency of the port-closingportion 20 of the reed member 19 toward flexure about a singlelongitudinally extending axis of curvature. a

More specifically, in the embodiment shown in FIG- URES 8 and 9, thereed plate 15 is recessed about each of the ends of the port 17 toprovide a seat 47 receiving a resilient insert 49 capable of conformingto the tendency of the port-closing portion 20 toward flexure about asingle lengthwise axis. In the embodiment shown in FIG- URE 10, the reedplate is recessed around the entirety a resilient insert 53.-

In general, if ports having outlines other than the illustrated,generally rectagula-r outlines are employed, the valve seats or edgesdefining such ports preferably should encourage reed flexure about asingle axis when the reed member is seated against the reed plate inport-closing relation thereto. Such seats or port edges therefore shouldlie in the surface of an imaginary curved surface having an axis andradius corresponding to the axis and radius of curvature of the reedmember under a condition of normal maximum flexure inwardly of the port.

Stress reduction can also be obtained by preventing fiexure of the reedmemberinto the port. More specifically, in the embodiment shown inFIGURE 11, the reed member is induced by the reed plate duringprogressive closure of the port, to assume a curvature about a singleaxis, which curvature is concave with respect to the reed plate. Suchconcave curvature tends to rigidify the reed member so as to preventsubsequent curvature about axes other than said single axis and therebyprevent the creation of peripheral stress waves such as are believed tooccur during reed member flexure about more than one axis.

Still more particularly, in FIGURE 11, the plate is provided with avalve seat which extends about the port and which, with respect to thereed member 19, presents a convexly curved surface 75. During closure ofthe reed member 19 against the seat, the reed member assumes the curvedconfiguration of the surface 75, thereby rigidifying the reed member 19against buckling or dishing into the port, and thereby avoiding thecreation, along the periphery of the reed member, of stress waves suchas are believed to commonly occur in response to dishing or bendingabout more than one axis. Alternatively, the reed member 19 can bepreformed with a curved configuration complementary to that of the reedplate seat surface 75, or the reed plate can be flat and the reed memberpreformed with a configuration which, with respect to the fiat reedplate seat, is concavely curved, thereby rigidifying the reed memberagainst flexure into the port.

In the illustrated embodiment, means are also provided in the reed plate15 for eliminating, or at least substantially reducing, adhesion betweenthe reed member and the reed plate due to accumulated oil on thecontacting surfaces thereof between the line 24 and the port 17. Suchmeans includes, in the plate 15, one or more grooves, recesses, orchanels 55 which extend across the reed plate 15 between the iner portedge 27 and the boundary line 24 of permanent engagement between thereed member and the plate, thereby reducing the area of contact betweenthe reed member and the reed plate, in the area between the port 17 andthe boundary line 24. The groove 55a adjacent to the line 24 alsoprovides a space for collecting any grit or foreign material which mayenter between the reed member and the reed plate, without affectingprogressive port-closing and portopening flexure of the reed member.

Reduction in impact stress can also be achieved by lengthening the timeinterval of impact through the provision of a resilient margin or insertaround all or a part of the port 17, such as the inserts 49 and 53already mentioned. Such resilient margins can also be used, as explainedabove, to permit reed member flexure about a single axis, particularlyif the end portions of the resilient margins are fabricated to be ofgreater yieldability than the lengthwise margins.

The reed member 19 is fabricated of resiliently flexible material, suchas stainless steel, and, in the disclosed construction, is generally ofrectangular configuration, including the port-closing portion 20 and aseries of spaced, generally parallel legs or segments 59 which extendfrom the port-closing portion 20 and are secured to the reed plate 15 bythe screws 23. The port-closing portion 20 of the reed member includesan outer edge 61 and side edges 63 and 65, and is dimensioned so thatwhen the reed member 19 is assembled to the plate 15, the outer and sideedges 61,

63, and 65, respectively, lap the seat area at the margin of the plate15 along the port edges 25, 29, and 31 by an amount within a range offrom about .010 to about .045 inch, preferably about .020 inch.Limitation of the lap to the above range lessens the area of the reedmember 19 subject to the effect of cyclical pressure variation, therebytending to reduce reed valve velocity and consequent reed member stress.Such limitation of lap also lessens the extent to which the outer andside edges 35, 37, and 39 of the reed member are dispiaceable from theplane of the reed plate 15 adjacent to the port 17 when the port isclosed. This feature is especially important in instances where reedmember flexure is not confined to curvature about a single axis.

The construction of the reed member 19 also serves to limit impactvelocity by the provision of the open area or cutouts 58 which definethe before-mentioned legs 59. As the cutouts 58 extend from at least theboundary line 24 of permanent engagement between the reed member and theplate to adjacent the edge 27 of the port 17, the total reed member areasubject to reaction to any pressure differential, during opening andclosing reed member movement, is thereby reduced.

Various of the features of the invention are set forth in the followingclaims.

What is claimed is:

1. A reed valve including a reed plate having therein means defining aport and a seat extending from and surrounding said port, a reed membersubject to curvature upon port closing operation and including a portclos ing portion, and means securing said reed member to said reed platefor movement of said port closing portion rela tive to said reed plateto and from a position of engagement with said seat, said reed memberoverlapping said seat by an amount less than about .045 inch along aportion of said seat which is most remote from said reed member securingmeans, said port being elongated and including a rectilinear edge at theintersection of said port and said remote portion of said seat, saidedge extending lengthwise of said port, and said seat having endportions including resilient means surrounding at least a portion ofsaid port and permitting displacement of the surface of said endportions.

2. A reed valve including a reed plate having therein means defining aport and a seat extending from and surrounding said port, a reed memberincluding a port closing portion subject to curvature upon port closingoperation, and means securing said reed member to said reed plate formovement of said port closing portion relative to said reed plate to andfrom a position of engagement with said seat, said reed memberoverlapping said seat by an amount less than about .045 inch along aportion of said seat which is most remote from said reed member securingmeans, said seat being fabricated of resilient material to affordconformance of the surface of said material to the curvature of the partof said port closing portion engaged against said seat.

References (Iited by the Examiner UNITED STATES PATENTS 978,152 12/1910Gutermuth 137525.5 1,029,726 6/1912 Sprado 137517 1,299,762 4/1919Nelson 137525.3 2,001,885 5/1935 Ohmart l37525.5 X 2,224,494 12/1940White 137527 2,616,403 11/1952 Kiekhaefer 137525.3 X 2,639,699 5/1953Kiekhaefer 12373 2,798,505 7/1957 Kehler 137516.11 2,851,054 9/1958Campbell 251368 X 2,885,178 5/1959 Mott 251-368 3,016,914 1/1962Keithahn 137-527 X 3,191,618 6/1965 McKim 137-5253 WILLIAM F. ODEA,Primary Examiner.

D. ZOBKIW, Assistant Examiner.

1. A REED VALVE INCLUDING A REED PLATE HAVING THEREIN MEANS DEFINING APORT AND A SHEET EXTENDING FROM AND SURROUNDING SAID PORT, A REED MEMBERSUBJECT TO CURVATURE UPON PORT CLOSING OPERATION AN INCLUDING A PORTCLOSING PORTION, AND MEANS SECURING SAID REED MEMBER TO SAID REED PLATEFOR MOVEMENT OF SAID PORT CLOSING PORTION RELATIVE TO SAID REED PLATE TOAND FROM A POSITION OF ENGAGEMENT WITH SAID SEAT, SAID REED MEMBEROVERLAPPING SAID SEAT BY AN AMOUNT LESS THAN ABOUT ABOUT .045 INCH ALONGA PORTION OF SAID SEAT WHICH IS MOST REMOTE FROM SAID REED MEMBERSECURING MEANS, SAID PORT BEING ELONGATED AND INCLUDING A RECTILINEAREDGE AT THE INTERSECTION OF SAID PORT AND SAID REMOTE PORTION OF SAIDSEAT, SAID EDGE EXTENDING LENGTHWISE OF SAID PORT, AND SAID SEAT HAVINGEND PORTIONS INCLUDING RESILIENT MEANS SURROUNDING AT LEAST A PORTION OFSAID PORT AND PERMITTING DISPLACEMENT OF THE SURFACE OF SAID ENDPORTIONS.